/Engine/Plugins/Runtime/GameplayAbilities/Source/GameplayAbilities/Public/GameplayEffectTypes.h
This is deprecated, use FOnGameplayAttributeValueChange.
typedef TMulticastDelegate_TwoParams< void, float, const [FGameplayEffectModCallbackData](API\Plugins\GameplayAbilities\FGameplayEffectModCallbackData) * > FOnGameplayAttributeChange